I appreciate the no-tool assembly, however it is difficult to assemble them and then move them to their place because the pieces easily fall out of place, no matter how hard they are placed. The issue is that the pieces do not snap together; instead, you slide two tabs in together to assemble each piece. I strongly recommend to assemble right where the shelf is supposed to go, otherwise some pieces will detach while moving it around. 
The frame pieces look and feel solid, though, and the shelves are sturdy. So far, I haven't put anything on them yet as they are part of a bigger project, but so far I am underwhelmed with its assembly. They work for me... but I would have preferred to have screw-on shelves. If they do not hold up after I put stuff in it, I'll update the review and lower it to a two. Right now It's more like 2.5 stars rather than 3.